Biology subjects

Sicklinger, F.

Publications and source records attributed to Sicklinger, F..

4 recordsLinked to original sources

bioRxiv2024

Spatial omics of acute myocardial infarction reveals a novel mode of immune cell infiltration

Myocardial infarction (MI) continues to be a leading cause of death worldwide. Even though it is well-established that the complex interplay between different cell types determines the overall healing response after MI, the precise changes in the tissue architecture are still poorly understood. Here we generated an integrative cellular map of the acute phase after murine MI using a combination of imaging-based transcriptomics (Molecular Cartography) and antibody-based highly multiplexed imaging (Sequential Immunofluorescence), which enabled us to evaluate cell-type compositions and changes at subcellular resolution over time. One striking finding of these analyses was the identification of a novel mode of leukocyte accumulation to the infarcted heart via the endocardium - the inner layer of the heart. To investigate the underlying mechanisms driving this previously unknown infiltration route, we performed unbiased spatial proteomic analysis using Deep Visual Proteomics (DVP). When comparing endocardial cells of homeostatic hearts and infarcted hearts, DVP identified von Willebrand Factor (vWF) as an upregulated mediator of inflammation 24 hours post-MI. To further explore the immune mediating capabilities of vWF and its effect on tissue repair, we performed functional blocking of vWF during acute murine MI. This resulted in a reduced amount of infiltration by CCR2+ monocytes and worse cardiac function post-MI. Our study provides the first spatial map of acute murine MI with subcellular resolution and subsequently discovers a novel route of immune infiltration. Furthermore, we identified vWF as a critical immune mediating agent for endocardial immune cell infiltration.

systems biology↗

bioRxiv2023

CXCL4-induced PBMCs Modulate Vascular Extracellular Matrix through Wnt5a-dependent Release of Calcific Extracellular Vesicles and Matrix Metalloproteinase-7

BackgroundMacrophage heterogeneity plays an increasing role in the study of vascular inflammatory responses. The CXCL4-induced monocyte/macrophage phenotype has previously been implicated with atherosclerotic plaque destabilization, a key process preceding plaque rupture. Monocyte-derived macrophages were found to exhibit a unique transcriptome in the presence of CXCL4 characterized by upregulation of S100A8 and MMP7. However, the mechanisms involved in CXCL4-induced monocyte-mediated vascular inflammation are unknown. MethodsSingle-cell RNA sequencing data were examined for CXCL4-dependent gene expression signatures in plaque macrophages. Human PBMCs were differentiated with CXCL4 and subsequently characterized in terms of osteogenic gene and protein expression signatures and calcific extracellular vesicle release. Association of the CXCL4-induced phenotype with the Wnt pathway was investigated, and CXCL4-induced PBMC-derived EV were analyzed for their potential to elicit an inflammatory response in vSMC. In-vitro findings were verified histologically in calcified human carotid artery plaques. ResultsIn human plaque macrophages, single-cell sequencing revealed a CXCL4-susceptible subpopulation bearing a distinct proinflammatory gene expression profile. CXCL4-differentiated PBMCs exhibited a marked induction of S100A8, MMP7 and osteogenic marker transcription concomitant with augmented release of calcific EVs enriched with MMP7, S100A8 and alkaline phosphatase. Under osteogenic conditions, increased overt calcification of the extracellular matrix was observed in vitro. Analysis of inflammatory pathway activation identified the paracrine Wnt5a-CaMKII signaling axis to be causally linked to the CXCL4-induced osteogenic PBMC phenotype, S100A8 and MMP7 enrichment as well as calcific potential of secreted EV. Additionally, CXCL4-polarized PBMC-derived EV differentially stimulated osteogenic/inflammatory genotype transition in vSMC. In human carotid artery plaques, occurrence of CXCL4-induced mononuclear cells coincided with Wnt5a-CaMKII pathway activation and progressive plaque calcification. ConclusionsThis study introduces a novel mechanism driving monocyte/macrophage-mediated extracellular matrix remodeling in calcific inflammatory responses through Wnt5a-CaMKII-activated secretion of MMP7+S100A8+ calcifying EV by CXCL4-induced pro-inflammatory monocytes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/540832v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1f81c66org.highwire.dtl.DTLVardef@107be9org.highwire.dtl.DTLVardef@37042forg.highwire.dtl.DTLVardef@1f3b0f3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Single-cell transcriptomics reveal distinctive patterns of fibroblast activation in murine heart failure with preserved ejection fraction

Inflammation, fibrosis and metabolic stress critically promote heart failure with preserved ejection fraction (HFpEF). Exposure to high-fat diet and nitric oxide synthase inhibitor N[w]-nitro-l-arginine methyl ester (L-NAME) recapitulate features of HFpEF in mice. To identify disease specific traits during adverse remodeling, we profiled interstitial cells in early murine HFpEF using single-cell RNAseq (scRNAseq). Diastolic dysfunction and perivascular fibrosis were accompanied by an activation of cardiac fibroblast and macrophage subsets. Integration of fibroblasts from HFpEF with two murine models for heart failure with reduced ejection fraction (HFrEF) identified a catalog of conserved fibroblast phenotypes across mouse models. Moreover, HFpEF specific characteristics included induced metabolic, hypoxic and inflammatory transcription factors and pathways, including enhanced expression of Angiopoietin-like 4 next to basement membrane compounds. Fibroblast activation was further dissected into transcriptional and compositional shifts and thereby highly responsive cell states for each HF model were identified. In contrast to HFrEF, where myofibroblast and matrifibrocyte activation were crucial features, we found that these cell-states played a subsidiary role in early HFpEF. These disease-specific fibroblast signatures were corroborated in human myocardial bulk transcriptomes. Furthermore, we found an expansion of pro-inflammatory Ly6Chigh macrophages in HFpEF, and we identified a potential cross-talk between macrophages and fibroblasts via SPP1 and TNF[a]. Finally, a marker of murine HFpEF fibroblast activation, Angiopoietin-like 4, was elevated in plasma samples of HFpEF patients and associated with disease severity. Taken together, our study provides a comprehensive characterization of molecular fibroblast and macrophage activation patterns in murine HFpEF, as well as the identification of a novel biomarker for disease progression in patients.

cell biology↗

bioRxiv2022

Transient inhibition of translation improves long-term cardiac function after ischemia/reperfusion by attenuating the inflammatory response

RationaleRapid reperfusion is the most effective treatment for attenuating cardiac injury caused by myocardial ischemia. Yet, reperfusion itself elicits damage to the myocardium through incompletely understood mechanisms, known as ischemia/reperfusion (I/R) injury. The myocardium adapts to I/R by changes in gene expression, which determines the cellular response to reperfusion. Protein translation is a key component of gene expression. However, it is unknown how regulation of translation contributes to cardiac gene expression in response to reperfusion and whether it can be targeted to mitigate I/R injury. MethodsTo examine translation and its impact on gene expression in response to I/R we assessed protein synthesis at different timepoints after ischemia and reperfusion in vitro and in vivo. Pharmacological inhibitors were used to dissect the underlying molecular mechanisms of translational control. Transient inhibition of protein synthesis was undertaken to decipher the effects of the translational response to reperfusion on cardiac function and inflammation. Cell-type-specific ribosome profiling was performed in mice subjected to I/R to determine the impact of translation on the regulation of gene expression in cardiomyocytes. ResultsReperfusion increased translation rates from a previously suppressed state during ischemia in cardiomyocytes, which was associated with the induction of cell death. In vivo, I/R resulted in strong activation of translation in the myocardial border zone. Detailed analysis revealed that the upregulation of translation is mediated by eIF4F complex formation, which was specifically mediated by the mTORC1-4EBP1-eIF4F axis. Short-term pharmacological inhibition of eIF4F complex formation by 4EGI-1 or rapamycin, respectively, attenuated translation, reduced infarct size and improved long-term cardiac function after myocardial infarction. Cardiomyocyte-specific ribosome profiling identified that reperfusion damage increased translation of mRNA networks in cardiomyocytes associated with cardiac inflammation and cell infiltration. Transient inhibition of the mTORC1-4EBP1-eIF4F axis decreased the expression of proinflammatory transcripts such as Ccl2, thereby reducing Ly6Chi monocyte infiltration and myocardial inflammation. ConclusionsMyocardial reperfusion induces protein synthesis in the border zone which contributes to I/R injury by rapidly translating a specific maladaptive mRNA network that mediates immune cell infiltration and inflammation. Transient inhibition of the mTORC1-4EBP1-eIF4F signaling axis during reperfusion attenuates this proinflammatory translational response, protects against I/R injury and improves long-term cardiac function after myocardial infarction. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABSO_LIThis is the first study to investigate the impact of translational regulation on cardiomyocyte gene expression in response to myocardial ischemia/reperfusion. C_LIO_LIWe show that translation regulates approximately two-thirds of differentially expressed genes in cardiomyocytes after ischemia/reperfusion, including many involved in inflammation and immune cell infiltration. C_LIO_LIThe translational response to ischemia/reperfusion is regulated by the mTORC1-4EBP1-eIF4F axis, which determines pro-inflammatory monocyte infiltration via control of the expression of the chemokine Ccl2. C_LI What Are the Clinical Implications?O_LICurrently, there are no specific therapies to prevent ischemia/reperfusion injury, which is mediated, at least in part, by a maladaptive inflammatory response. C_LIO_LIA translationally controlled network regulated by the mTORC1-4EBP1-eIF4F axis can be targeted by a short-term pharmacological intervention to attenuate the inflammatory response and improve cardiac function after ischemia/reperfusion in mice. C_LIO_LIThis study supports the emerging concept of selectively inhibiting maladaptive elements of the inflammatory response to improve outcome in patients after myocardial infarction; in addition, it provides a mechanistic basis for the currently ongoing CLEVER-ACS trial. C_LI

molecular biology↗